Does having 3G affect call quality or not? I received contradictory answeres to this question. Any experts that can tell me definitively

As long as you are in an area with good network coverage for both... Then there is no difference

I always keep my phone in dual mode just in case I hit a 3g dead spot cos that can cause dropped calls.

3G crypts the calls, while in 2G everybody with the special equipment+skills can hear your conversation